/*
 * Copyright 2008 ZXing authors
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.jwetherell.quick_response_code.qrcode.encoder;

/**
 * @author satorux@google.com (Satoru Takabayashi) - creator
 * @author dswitkin@google.com (Daniel Switkin) - ported from C++
 */
final class MaskUtil {

    private MaskUtil() {
        // do nothing
    }

    // Apply mask penalty rule 1 and return the penalty. Find repetitive cells
    // with the same color
    // and
    // give penalty to them. Example: 00000 or 11111.
    static int applyMaskPenaltyRule1(ByteMatrix matrix) {
        return applyMaskPenaltyRule1Internal(matrix, true) + applyMaskPenaltyRule1Internal(matrix, false);
    }

    // Apply mask penalty rule 2 and return the penalty. Find 2x2 blocks with
    // the same color and
    // give
    // penalty to them.
    static int applyMaskPenaltyRule2(ByteMatrix matrix) {
        int penalty = 0;
        byte[][] array = matrix.getArray();
        int width = matrix.getWidth();
        int height = matrix.getHeight();
        for (int y = 0; y < height - 1; ++y) {
            for (int x = 0; x < width - 1; ++x) {
                int value = array[y][x];
                if (value == array[y][x + 1] && value == array[y + 1][x] && value == array[y + 1][x + 1]) {
                    penalty += 3;
                }
            }
        }
        return penalty;
    }

    // Apply mask penalty rule 3 and return the penalty. Find consecutive cells
    // of 00001011101 or
    // 10111010000, and give penalty to them. If we find patterns like
    // 000010111010000, we give
    // penalties twice (i.e. 40 * 2).
    static int applyMaskPenaltyRule3(ByteMatrix matrix) {
        int penalty = 0;
        byte[][] array = matrix.getArray();
        int width = matrix.getWidth();
        int height = matrix.getHeight();
        for (int y = 0; y < height; ++y) {
            for (int x = 0; x < width; ++x) {
                // Tried to simplify following conditions but failed.
                if (x + 6 < width
                        && array[y][x] == 1
                        && array[y][x + 1] == 0
                        && array[y][x + 2] == 1
                        && array[y][x + 3] == 1
                        && array[y][x + 4] == 1
                        && array[y][x + 5] == 0
                        && array[y][x + 6] == 1
                        && ((x + 10 < width && array[y][x + 7] == 0 && array[y][x + 8] == 0 && array[y][x + 9] == 0 && array[y][x + 10] == 0) || (x - 4 >= 0
                                && array[y][x - 1] == 0 && array[y][x - 2] == 0 && array[y][x - 3] == 0 && array[y][x - 4] == 0))) {
                    penalty += 40;
                }
                if (y + 6 < height
                        && array[y][x] == 1
                        && array[y + 1][x] == 0
                        && array[y + 2][x] == 1
                        && array[y + 3][x] == 1
                        && array[y + 4][x] == 1
                        && array[y + 5][x] == 0
                        && array[y + 6][x] == 1
                        && ((y + 10 < height && array[y + 7][x] == 0 && array[y + 8][x] == 0 && array[y + 9][x] == 0 && array[y + 10][x] == 0) || (y - 4 >= 0
                                && array[y - 1][x] == 0 && array[y - 2][x] == 0 && array[y - 3][x] == 0 && array[y - 4][x] == 0))) {
                    penalty += 40;
                }
            }
        }
        return penalty;
    }

    // Apply mask penalty rule 4 and return the penalty. Calculate the ratio of
    // dark cells and give
    // penalty if the ratio is far from 50%. It gives 10 penalty for 5%
    // distance. Examples:
    // - 0% => 100
    // - 40% => 20
    // - 45% => 10
    // - 50% => 0
    // - 55% => 10
    // - 55% => 20
    // - 100% => 100
    static int applyMaskPenaltyRule4(ByteMatrix matrix) {
        int numDarkCells = 0;
        byte[][] array = matrix.getArray();
        int width = matrix.getWidth();
        int height = matrix.getHeight();
        for (int y = 0; y < height; ++y) {
            for (int x = 0; x < width; ++x) {
                if (array[y][x] == 1) {
                    numDarkCells += 1;
                }
            }
        }
        int numTotalCells = matrix.getHeight() * matrix.getWidth();
        double darkRatio = (double) numDarkCells / numTotalCells;
        return Math.abs((int) (darkRatio * 100 - 50)) / 5 * 10;
    }

    // Return the mask bit for "getMaskPattern" at "x" and "y". See 8.8 of
    // JISX0510:2004 for mask
    // pattern conditions.
    static boolean getDataMaskBit(int maskPattern, int x, int y) {
        if (!QRCode.isValidMaskPattern(maskPattern)) {
            throw new IllegalArgumentException("Invalid mask pattern");
        }
        int intermediate;
        int temp;
        switch (maskPattern) {
        case 0:
            intermediate = (y + x) & 0x1;
            break;
        case 1:
            intermediate = y & 0x1;
            break;
        case 2:
            intermediate = x % 3;
            break;
        case 3:
            intermediate = (y + x) % 3;
            break;
        case 4:
            intermediate = ((y >>> 1) + (x / 3)) & 0x1;
            break;
        case 5:
            temp = y * x;
            intermediate = (temp & 0x1) + (temp % 3);
            break;
        case 6:
            temp = y * x;
            intermediate = ((temp & 0x1) + (temp % 3)) & 0x1;
            break;
        case 7:
            temp = y * x;
            intermediate = ((temp % 3) + ((y + x) & 0x1)) & 0x1;
            break;
        default:
            throw new IllegalArgumentException("Invalid mask pattern: " + maskPattern);
        }
        return intermediate == 0;
    }

    // Helper function for applyMaskPenaltyRule1. We need this for doing this
    // calculation in both
    // vertical and horizontal orders respectively.
    private static int applyMaskPenaltyRule1Internal(ByteMatrix matrix, boolean isHorizontal) {
        int penalty = 0;
        int numSameBitCells = 0;
        int prevBit = -1;
        // Horizontal mode:
        // for (int i = 0; i < matrix.height(); ++i) {
        // for (int j = 0; j < matrix.width(); ++j) {
        // int bit = matrix.get(i, j);
        // Vertical mode:
        // for (int i = 0; i < matrix.width(); ++i) {
        // for (int j = 0; j < matrix.height(); ++j) {
        // int bit = matrix.get(j, i);
        int iLimit = isHorizontal ? matrix.getHeight() : matrix.getWidth();
        int jLimit = isHorizontal ? matrix.getWidth() : matrix.getHeight();
        byte[][] array = matrix.getArray();
        for (int i = 0; i < iLimit; ++i) {
            for (int j = 0; j < jLimit; ++j) {
                int bit = isHorizontal ? array[i][j] : array[j][i];
                if (bit == prevBit) {
                    numSameBitCells += 1;
                    // Found five repetitive cells with the same color (bit).
                    // We'll give penalty of 3.
                    if (numSameBitCells == 5) {
                        penalty += 3;
                    } else if (numSameBitCells > 5) {
                        // After five repetitive cells, we'll add the penalty
                        // one
                        // by one.
                        penalty += 1;
                    }
                } else {
                    numSameBitCells = 1; // Include the cell itself.
                    prevBit = bit;
                }
            }
            numSameBitCells = 0; // Clear at each row/column.
        }
        return penalty;
    }

}
